1. Field of the Invention
Embodiments of the invention relate to a medical fixation device. More particularly, but not by way of limitation, at least one embodiment enables a system for temporary fixation of an implantable medical device such as a short lead pacemaker outside of the heart and in a large blood vessel such as the inferior vena cava. The fixation mechanism or element is temporary in nature in that the fixation holds the implantable medical device in place until the implantable medical device is grown in to the wall of the vessel and the short lead attached to the implantable medical device and implanted in the heart is grown in. The cell tissue surrounding the implantable medical device and the short lead then keeps the implantable medical device in place without the temporary fixation element.
2. Description of the Related Art
Traditional cardiac rhythm management or CRM devices include medical devices that are usually implantable and permanently connected to electrode leads for delivery of electrical stimulations pulses to the tissue or myocardium of a human heart. Typically, the electrodes are coupled to the myocardium through intravenous or epicardial leads, so that the housing of the pacemaker may be placed remotely to the heart. This type of pacemaker is shown in FIG. 1 that specifically illustrates a three chamber pacemaker 10 connected to pacing/sensing leads placed in a heart 12. The pacemaker 10 is coupled to the heart 12 by way of leads 14, 16 and 30.
Lead 14 is implemented with a pair of right atrial electrodes 18 and 20 that are in contact with the right atria of the heart 12, and the lead 16 implemented with a pair of electrodes 22 and 24 that are in contact with the right ventricle 28 of heart 12. The electrodes 18 and 22 are tip-electrodes at the very distal end of leads 14 and 16, respectively. Electrodes 20 and 24 are implemented as ring electrodes in close proximity but electrically isolated from the respective tip electrodes 18 and 22. Also shown is electrode lead 30 that includes a left ventricular tip electrode 32 at the distal end.
Presently the CRM device industry is investigating new products called “leadless pacemakers”. These leadless devices minimize potential lead breakages and pocket infections. Based on technology advances of integrated circuits and batteries, implantable pacemakers can be built so small that the entire device may be implanted directly into the heart. Depending on the place of implant, for example atrium or ventricle, and the size of the heart chamber relative to the length of the leadless pacemaker, one potential problem is that the pacemaker may touch the cardiac valve, which separates the atrium form the ventricle. If the pacemaker touches the cardiac valve, blood regurgitation may occur. Another problem relates to the size limitations of these types of leadless pacemakers wherein based on the small size, the pacemakers may be limited in their functionality. For example, due to size constraints, small pacemakers may not provide statistics of detected cardiac events or wireless telemetry. An example “leadless” pacemaker is shown in FIG. 2. As shown when pulse generator 10′ senses electrical activity from right ventricular electrode 22 for example, the pulse generator 10′ sends an ultrasonic pulse to wireless electrode 32′, which powers and/or otherwise causes a pace event in the left ventricle.
For at least the limitations described above with respect to leadless pacemakers, there is a need for a system for temporary fixation of an implantable medical device such as a short lead pacemaker in a large blood vessel such as the inferior vena cava.